The anion transport system in the erythrocyte membrane is necessary for the rapid transport of CO2 from the tissues to the lungs. This proposal seeks funds to determine the structural bases of several kinetic properties of anion exchange across the erythrocyte membrane, and to determine the types of structural perturbations in the transport system which lead to reduced rates of anion exchange. Evidence is presented to suggest that the anion transport system may be composed of several different structural components which associate by means of noncovalent or weak interactions. The association reversible yields dissociation equilibrium of the transport system components may be affected by pH, ionic strength, ionic composition and the presence of reversible noncompetitive inhibitors of anion transport. The major emphasis of this proposal is directed towards an investigation of this dissociation equilibrium as a function of the above solution variables. Several correlations are also shown between the ability of an anesthetic to inhibit anion transport in erythrocytes and the potency of the anesthetic in blocking nerve conduction. One anesthetic, benzyl alcohol, appears to dissociate the anion transport system components and to inhibit anion transport. Thus, the exchange of anions across the red cell membrane might provide a valuable model system for the study of anesthetic action. The major techniques in these investigations include calorimetry, rate zonal sedimentation analysis, fluorescence spectroscopy, crosslinking experiments, measurements of anion exchange rates, and several new procedures recently developed by the applicant.